residential design in flood affected heritage areas

107 Pages·2016·44.6 MB·English

residential design in flood
affected heritage areas
maitland city council
Executive Summary
Maitland City Council is currently updating its planning controls for residential development in its
flood affected, heritage conservation areas and in particular, Central Maitland. In line with Council’s
objectives, James Davidson Architect was commissioned to undertake a design exercise for three
building typologies (detached, dual occupancy and multi-unit dwelling) on three vacant sites in
Central Maitland. In addition to this we were engaged to provide Council with guidance and ideas on
on second storey, rear additions to three other sites with existing single storey houses. In responding
to this commission, and prior to beginning the design exercise, we combined our existing knowledge
of flood resilient design principles with an extensive analysis of Maitland’s eclectic heritage conditions
to develop a Maitland-specific palette of materials, elements and building practice to inform our
heritage and flood resilience design synthesis. This architectural palette includes the use of flood
plinths, voids, permeable and semi-permeable undercrofts, open verandah spaces, courtyards,
garden terraces and flood resilient building materials and principles, which are in themselves all
complementary to Maitland’s heritage and character traditions as well as useful in ameliorating the
effects of flooding.
All 15 house designs (9 new builds and 6 rear additions) accord with the Maitland Development
Control Plan in maintaining habitable uses above the Flood Planning Level and non-habitable uses
below. On sites (Victoria Street for example) where the FPL is 4.4m above the ground level this was
certainly a challenge, however, with the establishment of the heritage/flood palette we believe we
have been able to overcome such constraints, to the point of seeing them rather as opportunities
for the creation of new residential architectural forms, not only for Maitland, but Australia generally.
On those sites where the FPL is quite high, we have worked hard to respect (not over-scale) the
surrounding streetscape by incorporating a range of different design mechanisms to reduce building
bulk. These include the use of verandah spaces to the street, activation of the non-habitable activity
spaces in the undercroft of particular dwellings and the specific use of garden planters, fencing,
screening and vegetation. Also, the combination of terraces, flood plinths and void spaces are key
principles in facilitating the transference of belongings between lower and upper levels prior to and
during an inundation event; while the use of resilient building materials and construction systems
under the FPL make cleaning and re-establishing life easier after a flood.
In developing planning controls to encourage good design outcomes, we recommend that Maitland
City Council consider expanding on the NSW Floodplain Development Manual definition of ‘non-
habitable use’ so as to stimulate a greater variety of activities and uses in the undercroft spaces
under the FPL that do not threaten the safety of occupants, but add colour and vibrancy and assist in
improving issues of building bulk and scale to the street. This may well also be a consideration for the
National Construction Code. In addition, we hope that the establishment of a flood/heritage palette
of materials and building typologies will further assist Council in revitalising the conservation zone of
Central Maitland in a way that not only challenges contemporary perceptions regarding the effects of
flood but shows that good design thinking can actually advocate for, and propose, new architectural
forms previously unheard of.
Contents
Executive Summary
Project Brief

Definitions and Abbreviations 1
List of Abbreviations
Definitions
Introduction 2
Maitland City
Scope of Works
Methodology 3
Heritage
Flood Design
Flood Aware Design Requirements
Our Experience in Flood Design 4
Heritage Principles and Strategies 6

Flood Principles and Strategies 7
Heritage and Flood Synthesis 8
Maitland: Context Analysis 10
Site Responses: Rear Addition Sites 12
Hunter St
Charles St
Carrington and James St
Site Responses: New Build Sites 48
Carrington and Radford St
Catherine St
Victoria St

References 98
Project Brief (Maitland City Council)
Residential Design in Flood Affected Heritage Areas
Residential development within Central Maitland is one of the strategies that Council believes may
help revitalise the area. To this end, it is committed to increase the resident population to a pre-1955
level of at least 5,500 people. The estimated residential population as of 2014 was 2,238. Central
Maitland is zoned B4 Mixed Use, R1 General Residential and B3 Commercial Core. Height limits and
floor space ratios are undefined except in the B3 Commercial Core zone. These are determined on
a merit-based assessment. All of Central Maitland is within a Heritage Conservation Area. One of the
challenges that Council faces in Central Maitland is achieving good design outcomes while ensuring
that adequate protection is provided against flood events. The existing policy is that the finished
floor level of habitable areas is to be at a height equalling the “flood planning level” (1% Annual
Exceedance Probability plus 0.5m). Council considered permitting an area of habitable space (50%)
below the flood planning level (FPL) in an effort to achieve more appealing built outcomes. However,
legal advice identified that Council may be liable if it adopted the policy. That policy was abandoned.
Therefore, apart from minor additions to existing dwellings, Council’s policy is that no habitable floor
space is to be provided below the FPL. Furthermore, Council is currently participating in a NSW
State Government initiative to provide financial support to raise flood affected houses to the flood
planning level. The initiative contributes two-thirds of the cost of raising the house. It is expected that
this will create interest in raised existing houses.
The policy to not allow habitable floor space below the FPL imposes a challenging design
consideration for development within heritage conservation areas. In particular Council is trying to
avoid deactivated voids beneath the building and a streetscape dominated by car garages. There are
also other challenges including a variety of heritage styles and built forms. To address this, Council
intends to prepare development controls to encourage good design outcomes in these circumstances.
To inform these controls, Council is seeking an architectural firm to undertake a design exercise for
three sites in Central Maitland. The exercise should produce designs including materials for three
building typologies: detached dwelling; dual occupancy; multi-dwelling housing for each site. The
designs will be used to illustrate appropriate design responses and help inform the development
controls relating to residential development in flood affected, heritage conservation areas. Council
encourages a variety of traditional and contemporary responses. Another development scenario
where Council has had difficulty in generating development controls to achieve good design
outcomes is two-storey rear additions to existing houses within the FPL. The Maitland Development
Control Plan (DCP) allows an extension of up to 50% of the existing floor space below the FPL.
To assist in the development of planning controls and to illustrate good design outcomes, Council
wishes for the architectural firm to design a 2-storey rear addition that responds to the site, street and
heritage context for three nominated sites. Once again, Council encourages a variety of traditional
and contemporary responses. Council recently adopted the Hunter River Floodplain Development
Control Plan that applies to all areas below the flood planning level across the local government area.
That DCP includes development provisions for residential development. It is anticipated that the
outcome of this project will provide the basis for amendments to the Maitland Development Control
Plan 2011 for residential development in flood affected, heritage areas including Central Maitland.
Definitions and Abbreviations
PMF Probable Maximum Flood
ARI Average Recurrence Interval
AHD Australian Height Datum
DEP Development Control Plan
FMC Floodplain management Committee
FPL Flood Planning Level - FPL = 1% AEP flood level + 0.5m
FPM’s Flood Planning Maps
FRMSP Floodplain Risk Management Study Plan
LEP Local Environmental Plan
LGA Local Government Area
MCC Maitland City Council
NCC National Construction Code (formerly Building Code of Australia)
NHU Non-Habitable Use
Habitable Space
“Habitable room means a room used for normal domestic activities, and—
(a) includes a bedroom, living room, lounge room, music room, television room, kitchen, dining room,
sewing room, study, playroom, family room, home theatre and sun room; but
(b) excludes a bathroom, laundry, water closet, pantry, walk-in wardrobe, corridor, hallway, lobby,
photographic darkroom, clothes-drying room, and other spaces of a specialised nature occupied
neither frequently nor for extended periods.” (NCC Vol 2. 2016)
“In a residential situation: a living or working area designed, constructed or adapted for activities
normally associated with domestic living, such as lounge room, dining room, rumpus room, kitchen,
bedroom or workroom. A garage, storage room, laundry, lobby, bathroom or external verandah,
balcony or terrace is not categorised as a habitable room. (Maitland DCP 2011)
1:100 Average Recurrent Interval
The 1% AEP flood is a statistical event occurring on average once every 100 years, ie; there is a
1% chance of a flood of this size or greater occurring in any given year. The 1% AEP flood event is
generally used to limit flood exposure and damage to standard residential development. (New South
Wales Government 2005 A-1.)
Detached Dwelling
A building containing only one dwelling.
Dual Occupancy Dwelling (Attached and Detached)
Dual Occupancy (attached) means 2 dwellings on one lot of land that are attached to each other, but
does not include a secondary dwelling. Dual Occupancy (detached) means 2 detached dwellings on
one lot of land, but not does not include a secondary dwelling.
Multi-Dwelling (Attached and Detached)
3 or more dwellings (whether attached or detached) on one lot of land, each with access at ground
level, but does not include a residential flat building.
Reference Level
A height plane used as a basis to compare or inform a design decision
1
Introduction
Maitland
The area of Central Maitland is in the Hunter River floodplain and has a long history of flooding, the
most serious occurring in 1955. Central Maitland has reduced in population by half since. Central
Maitland is a Heritage conservation area and is culturally significant to the residents of Maitland.
There is a significant history of flood resilience in Maitland’s building practice. High Street is the spine
from which the majority of streets branch off at an acute angle. The original bullock track became
fixed as the line of the main street enclosed by buildings of two-three storeys, and punctuated along
its length by landmark or “reference buildings.” Throughout its development, the two storey building
has dominated the streetscape with only a few instances of one or three storey buildings occurring.
Maitland’s prominence as a trading centre meant that development and redevelopment was always
taking place and, in many areas, the present buildings might be the third or fourth buildings on
the site. This process of growth and redevelopment has caused some unusual groups of buildings
- each building being different from one another in style and period - occurring in various parts of
the town: for examples, Bourke Street, in the heart of the residential area, contains buildings dating
from the 1850s, 1880s, 1890s and 20th Century. The earliest buildings for which dates are known are
residential buildings which have survived largely because they are on the edge of town, away from
the business centre and also because they are of masonry construction and have withstood flooding
over the years. (DCP, p2)
Scope of works
1. To undertake an architectural design exercise for three nominated, vacant sites in Central Maitland
2. To prepare site analysis plans, illustration and commentary for each site
3. To prepare site plans, floor plans (limited to use zones) and relevant elevations for three building
types (detached dwelling, attached dwelling, multiunit dwelling) for each site
4. To prepare design notes on key considerations in the design process
5. To prepare designs for 2-storey rear additions to three, nominated residences in Central Maitland
6. To prepare site plans, floor plans (limited to use zones) and relevant elevations for each site
2
Methodology
Our Approach
The designs presented in this report augment Maitland’s historical approach to flood resilience in a
contemporary way that respects both tradition and heritage. We see an opportunity for a meaningful
synthesis between heritage and flood design principles. As such, our design approach draws from the
design principles and criteria outlined in the Maitland Development Control Plan in conjunction with
the Design in Context: Guidelines for Infill Development in the Historic Environment report prepared
for the NSW Heritage Division (2005), and the Reducing Vulnerability of Buildings to Flood Damage
report for the Hawkesbury-Nepean Floodplain Management Steering Committee (2006).
Heritage
In terms of heritage design in Maitland, we have identified the following as important design
criteria:
• Respect the history and existing patterns in the natural and built environment
• Respect the existing surrounding landscape and environment
• Respect the existing land use patterns, morphology, allotment patterns streetscape, setbacks,
scale, materiality, form and typology
Flood Design
Development in the floodplain has the potential to result in significant costs. Since flooding may only
occur infrequently it may be tempting to overlook the consequences resulting in a relatively high risk
of flood damages. Key factors retaining to property risks are as follows:
• The depth and velocity of floodwaters, which are directly related to the potential for structural
damage
• The potential for damages to property across a range of flood events
• The potential for the development to increase the flood affectation and likely damages for existing
and future development on the floodplain, including consideration of cumulative development of
an area; and
• The potential for other social, economic or environmental costs as a result of the development
(DCP p2)
Residential design in flood affected Central Maitland should minimise risk to property and ensure the
safety of residents by :
• Acknowledging the existing pattern of development in Maitland
• Using suitable materials below and above the FPL to aid efficient restoration and re–occupation of
property after flooding
• Allowing for the protection of property during the event of a flood with the provision of adequate
dry storage above the FPL in the event of a flood
• Allowing for the timely, orderly and safe evacuation of residents during a flood event (DCP p3)
Flood Aware Design Requirements
The design approaches evident in this report accord with the principles and criteria outlined in Table
1 (Flood Aware Design Requirements for Residential Development on Flood Prone Land) of the
Maitland Development Control Plan.
3
Our Experience in Flood Design
James Davidson Architect has become a leader in architectural approaches to flood design, having
undertaken a range of research projects, pro-bono community work and built commissions since the
floods in Queensland in 2011. Our approach to flood design focuses on principles of ‘wet-proofing’,
the concept of allowing water to flow through the non-habitable spaces under a building with little
damage. Over the last 5 years, the practice has designed a number of flood resilient housing projects
all of which have been seen through to construction. Stemming from our pro-bono services, much
of our practice work focuses on maintaining affordability, particularly in light of planning restrictions.
Using wet-proofing principles we aim to create flexible non-habitable spaces which ameliorate
aesthetic concerns and maximise value to both the homeowner and wider community.
Fairfield House
This post war house in Fairfield, Brisbane was flooded throughout its ground floor spaces. Upon
reconstruction, the clients desired not only to raise the existing house higher, but rebuild in underneath
with flood-proof materials. This resulted in the development of experimental and conventional ideas
at all scales of residential design and construction. Single skin designer block masonry with polished
concrete floors are combined with sunken sill details to allow easy washing out of future floodwaters.
Cabinets on the ground floor are constructed of resilient materials, with bench-tops standing on
their own frame. Removable cabinets underneath allow for ease of cleaning. These techniques will
substantially reduce repair costs in a future flood, not to mention reduce insurance premiums. The
combination of flood friendly materials with strategic planning between the non-habitable ground
and habitable upper floor allowed an exciting aesthetic while importantly providing spatial flexibility
for the clients.
Graceville House
Only a few hundred metres from the Brisbane River and backing on to flood prone parkland, this
property at Graceville flooded extensively above the ground level. The clients were forced to raise
their house over 5 metres to comply with new temporary planning instruments, which required
habitable floor levels at 500mm above the 2011 flood-line. Prominent features of this building include
the use of water-resilient affordable building materials for the lower floor. The sloping ground level
was raised to a plinth to address issues of height and scale particularly on the street front as well as
assisting to maintain ease of access to the backyard. Flood-proof joinery was installed on the ground
level. Hardwood timber was used for permeable screens and the stair, which is more resistant to
future flood water while providing cross-ventilation and passive cooling in normal conditions.
West End House
Sited directly opposite the West End banks of the Brisbane River, the flooding risk this property
faces is visually evident. As a traditional Queenslander with hardwood flooring and wall finishes,
the building itself escaped relatively unscathed, meaning that only the kitchen and bathroom were
damaged beyond repair. Using the opportunity to maximise the location of the property, the clients
wished to build a flood friendly habitable space below the existing building. Utilising similar finishes
and details to our other flood houses, the building as a whole serves as an excellent example of a
typological combination of a traditional Queenslander renovated with new, alternative flood resilient
materials. Resilient materials and construction details allow
NEW & EXISTING LEVELS
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FOR USE DURING CONSTRUCTION
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BENCHTOP
SUPPORT
NEW
FLOOD
REMOVABLE PLY MODULE
EXISTING
Permeable elements and a plinth mitigate issues Modular elements allow extra flexibility within a
of scale and the streetscape after house raising. heritage or character context.
Graceville House West End House
5
Heritage Principles and Strategies
Heritage Principles
In addition to the physical and tangible heritage of buildings we also identify the need to retain
and enhance Maitland’s intangible heritage, potentially through the use of flexible building patterns Character:
that encourage occupiers to modify and adapt their living and work spaces over time. The following
Background Additions
design criteria have been drawn from the NSW Heritage Division Guidelines:
• Character of street front should be maintained and enhanced
• Scale building envelopes to preserve and build on existing streetscape character
• Form should complement the existing buildings in the area
• Materials used should be common to the area
• Siting should provide access to pedestrians and vehicles in a way which adds to street character
• Programme non-habitable space ambiguously to allow flexibility, affordability and evolution over
time
Heritage Strategies
In building on the heritage principles above, we have identified the following architectural strategies:
Form:
Character: Background Additions
Use form as a background infill, creating another layer setback to the rear. Side Additions
Scale: Reference Heights
DIAGRAMS
Create layers of datums corresponding to surrounding character/heritage (verandahs, floor levels,
AE-203
balustrades, sills, heads, eaves and ridge lines).
MAITLAND CONSULTANCY
Form: Side Additions
Work with existing roofs, reflecting formal lines of contextual datums and terraces or; expand working
with footprints of service buildings, sheds, water towers and their materiality and scale.
Siting: Terracing
Concrete slab-on-ground to replace stumps, building on formal principle of datums
Scale:
Materials: Construction Detail
DIAGRAMS
Elevated verandahs sitting on plinths to achieve reference datum levels. Reference HeigAhE-20t3s
MAITLAND CONSULTANCY
PInrcolugdrea mnomne-habitable areas such as temporary work areas which potentially enliven the street and Building DIAGRAMS
AE-203
maintain connection with ground.
MAITLAND CONSULTANCY
Front Yard
Verandah
Siting:
Terracing
FOR USE DURING CONSTRUCTION
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PLOT DATE:27/06/2016 9:11:52 AM